 An obstetric ultrasound is used to produce pictures of a developing embryo and the mother's uterus and ovaries. For scans done in early pregnancy, you're required to have a full bladder. For scans in the second and third trimester, you need to have eaten well to ensure that the baby is active. On the day of the scan, you'll be settled comfortably in a private area and you need to remove all accessories. Please inform the doctor about your medical history. Gel will be applied to the abdomen to provide better contact between the skin and the scanner. Obstetric ultrasound is best if the fetus is examined in different positions to optimally visualise the fetal parts. Pictures are sent instantly to a nearby monitor. The doctor may have to push quite firmly at times to see the deeper structures. The excess gel is wiped off gently after the scan. The procedure usually takes about 30 minutes. As the desired fetal positions may not be obtained in one sitting, multiple sittings may be required.